REPORT 


OP  THE 

SECRETARY  OF  THE  NAVY, 

Communicating,  in  Compliance  with  a Resolution  of  the  Senate, 

A Report  of  the  Engineer-in-Chief  of  the  Navy,  on  the 
Comparative  Value  of  Anthracite  & Bituminous  Coals. 


MAY,  1852. 


R3BPORT 

OF.  THE 

SECRETARY  OF  THE  NAVY, 

COMMUNICATING,  IN  COMPLIANCE  WITH  A RESOLUTION  OF  THE  SENATE, 

A Report  of  the  Engineer-in-Chief  of  the  Navy,  on  the  Com- 
parative Value  of  Anthracite  and  Bituminous  Coals. 


May  24,  1852 — Ordered  to  lie  on  the  table. 

May  27,  1852 — Referred  to  the  Committee  on  Naval  Affairs,  and 
ordered  to  he  printed. 


Navy  Department,  May  21,  1852. 

Sir  : I have  the  honor  to  submit  the  enclosed  report  of  the  Engineer- 
in-chief  of  the  Navy,  on  the  comparative  value  of  anthracite  and  bitu- 
minous coals,  called  for  by  a resolution  of  the  Seuate,  passed  on  the  17th 
instant. 

I have  the  honor  to  be,  sir,  with  high  respect,  your  obedient  servant, 

C.  M.  CONRAD, 

, Acting  Secretary  of  the  JSTavy. 

Hon.  Wm.  R.  King,  President  of  the  Senate. 


Office  of  Engineer-in-Chief,  U.  S.  N.,  ) 
February  24,  1852.  ] 

Sir  : In  compliance  with  your  instructions,  made  in  conformity  to  the 
orders  of  the  Navy  Department  in  June  last,  to  test  the  comparative  value 
of  Anthracite  and  Bituminous  Coals  for  the  purpose  of  generating  steam, 
I have  the  honor  to  report : 

That  on  the  completion  of  the  pumping  engine  of  the  dry  dock  of  the 
New  York  Navy  Yard,  I caused  experiments  to  be  made  with  bituminous 
(Cumberland)  and  Anthracite  (white  ash)  Coals;  and  also  on  the  oomple- 
tion  of  the  United  States  steamer  “Fulton,”  in  January  last,  I made  a 


2 


series  of  experiments  with  the  same  varieties  of  coals : the  condensed 
results  of  all  which  are  herein  given.  In  addition,  I would  also  state, 
that  the  United  States  steamer  “ Fulton”  has  been  on  constant  duty 
several  days  since  the  experiments  were  made,  burning  constantly  White 
j^sh  Anthracite. 

From  a letter  from  her  chief  engineer,  H.  Hunt,  Esq.,  detailing  her 
performance  for  the  first  four  days,  I extract  the  following  : The  engine 
worked  as  well  as  any  I ever  saw,  but  the  boilers  exceeded  my  calcula- 
tions ; with  clean  fires  very  easily  keeping  forty  pounds,  cutting  off  at 
half  stroke  without  blowers.  I will  here  predict  that  she  (the  ‘‘Fulton”) 
will  do  more  service  at  less  expense,  than  any  steamer  government  will 
have  in  five  years.  Whilst  she  was  out  on  the  first  four  days  I was  in  her, 
we  were  frequently  shut  off  or  cutting  off  to  run  slow,  and  turning  around, 
running  from  one  vessel  to  another,  so  no  calculations  could  be  made  of 
her  speed  or  slip  of  wheel.  The  furnace  doors  were  open  full  half  the 
time,  to  keep  steam  down,  so  much  more  fuel  was  used  than  necessary,  but 
the  nature  of  our  service  was  such,  that  it  could  not  be  avoided.” 

In  consequence  of  the  ill  health  of  the  chief  engineer,  he  was  not  able 
to  return  in  her  second  trip ; the  results  of  her  consumption  of  coal  on 
that  occasion,  are  therefore  extracted  from  a letter  written  by  the  assistant 
engineer,  S.  McElroy,  showing  the  following  ; “Running  time  with  White 
Ash  Anthracite,  January  25  to  28,  seventy-one  hours.  Total  coal  used, 
69,480  pounds,  average  992 pounds  per  hour.”  The  above  extracts  are 
made,  not  because  they  are  the  most  favorable  which  occur  in  the  log,  but 
as  they  show  the  action  of  the  engine  and  boilers  for  several  consecutive 
hours.  Nothing  can  be  smoother  than  the  motion  of  the  engine  under 
ordinary  running  circumstances  ; and  in  relation  to  the  generative  power 
of  the  boilers,  it  is  more  difficult  to  keep  steam  down  than  up. 

It  is  unnecessary  to  use  the  blowers  for  ordinary  work,  as  the  natural 
draught  proves  abundantly  sufficient  for  twenty  to  twenty-five  pounds  of 
steam,  with  sixteen  to  eighteen  turns ; although  they  are  undoubtedly  of 
great  value  in  cases  of  emergency,  and  necessary  to  the  prompt  and  proper 
management  of  the  fire  room,  with  Anthracite  Coal.  The  “ Fulton”  will 
have  no  difficulty  whatever  in  making  twelve  knots  in  ordinary  sea  weather 
as  long  as  the  bunkers  hold  out. 

A more  extended  series  of  experiments  would  undoubtedly  be  more 
favorable  to  the  anthracite,  owing  to  the  fact  that  small  quantities  were 
put  in  the  furnaces  and  almost  entirely  consumed  while  the  engine  was 
working ; it  being  well  known  that  a small  body  of  bituminous  coal  will 
burn  longer  than  the  same  amount  of  anthracite  spread  thinly  over  the 
grates. 

The  cost  of  the  two  kinds  of  coals  used  in  the  experiments  were  as 
follows,  at  the  New  York-Navy  Yard : anthracite  |3  90  per  ton,  bitumi- 
nous ^5  65  per  ton. 

I have  made  no  comparison  of  the  relative  costs  of  the  two  kinds  of 
coal,  as  it  may  vary  according  to  different  localities  and  periods  of  delivery, 
and  cannot  therefore  be  considered  a fixed  element ; but  have  confined  the 
results  entirely  to  their  generating  powers,  deduced  from  the  following 
experiments. 


3 


1.  Experiments  with  bituminous  coal,  made  with  the  boilers  of  the  United 

States  steamer  Fulton,  at  the  J^ew  York  Jfavy  Yard,  January,  1852. 

The  temperature  of  the  water  in  the  boilers  being  at  38^  F.,  and  the 
temperature  of  the  boiler  room  18°,  the  fires  were  lighted  at  ten  hours 
thirty  minutes,  A.  M. 

At  eleven  hours  forty  minutes,  A.  M.,  the  temperature  of  the  water  was 
212°  F.,  and  steam  began  to  be  generated  at  the  atmospheric  pressure.- 
Time  raising  steam,  seventy  minutes.  The  temperature  of  the  boiler-room 
had  now  increased  from  18°  to  32°  F.  At  eleven  hours  fifty-four  minutes 
A.  M.  the  steam  pressure  in  the  boilers  was  thirty  pounds  per  square  inch 
above  the  atmosphere.  Time  of  obtaining  thirty  pounds  of  steam,  one  hour 
twenty-four  minutes  from  a temperature  of  32°  F.  Up  to  this  time  there 
had  been  fed  into  the  furnaces  one  thousand  pounds  of  dry  pine  wood,  equal 
to  five  hundred  pounds  of  coal,  and  two  thousand  eight  hundred  and  twenty- 
six  pounds  of  (Cumberland)  bituminous  coal.  Total,  three  thousand  three 
hundred  and  twenty-six  pounds. 

The  engine  was  now  set  in  operation  to  work  off  all  the  steam,  which 
the  above  amount  of  coal  would  generate,  no  more  being  fed  to  the  furnaces. 
In  fifty-three  minutes  the  steam  pressure  was  reduced  from  forty  pounds  to 
five  pounds,  and  the  number  of  double  strokes  of  piston  made  from  forty-one 
to  seven,  when  the  engine  was  stopped.  During  the  time  the  engine  was 
in  operation,  the  steam  was  cut  off  at  half  stroke. 

The  engine  consisted  of  one  cylinder,  fifty  inches  diameter,  and  ten  feet 
four  inches  stroke.  The  space  between  cut  off  valve  and  piston,  including 
clearance,  to  be  filled  with  steam  per  stroke  is  3.094  cubic  feet.  The  cal- 
culation of  the  amount  of  water  evaporated  is  made  from  the  quantities  of 
steam  measured  out  by  the  cylinder,  divided  by  the  relative  bulks  of  steam 
of  the  experimental  pressures  and  the  water  from  which  it  is  generated. 

The  initial  pressure  of  the  steam  in  the  cylinder  is  taken  at  one  pound 
less  than  in  the  boilers.  The  space  displacement  of  piston  filled  with  steam, 
per  stroke  is  70.448  cubic  feet,  to  which  must  be  added  the  above  3.094 
cubic  feet,  making  a total  of  73.542  cubic  feet. 


Time. 

Mean  pressure  above  at- 
mosphere, per  square 
inch,  in  cylinder. 

Number  of  double  strokes 
of  piston  made. 

Cubic  feet  of  water 
evaporated. 

MINUTES. 

POUNDS. 

6 

32^ 

41 

10.326 

5 

25 

34 

7.311 

5 

22i 

32 

6.483 

6 

19  i 

3U 

5.879 

5 

16^ 

31 

5.352 

5 

14 

30 

4.796 

5 

Hi 

26 

3.797 

5 

9 

23 

3.075 

5 

7i 

21 

2.631 

6 

5i 

12 

1.393 

2 

4i 

7 

0.868 

51.911 

4 


Taking  the  weight  of  a cubic  foot  of  sea  water  at  64.3  pounds,  the  total 
weight  evaporated  is  (51.911  X 64. 3)=:3337. 877  pounds.  The  boilers  of 
the  Fulton  contained  82.000  pounds  of  water  at  the  initial  temperature  of 
32°  F.,  which  was  raised  to  212°  F.,  and  3337.877  pounds  of  it  evaporated 
by  three  thousand  three  hundred  and  twenty-six  pounds  of  coal. 

Now  it  requires  five  times  and  a half  as  much  caloric  to  evaporate  a given 
•bulk  of  water  from  a temperature  212°  F.  as  to  raise  it  to  that  temperature 
from  32°  F.  The  quantity  of  fuel,  therefore,  expended  in  raising  the  water 
from  the  initial  temperature  to  that  of  212°  F.,  compared  to  that  expended 
in  evaporating  the  3337.877  pounds  from  that  temperature,  will  be  as 
(82.000xl80°)=14,760,000  to  (3337.877x990°)=3,304, 498.23,  or  as 
4.4666  to  1.000;  consequently  pounds  of  coal  were  con- 

sumed in  evaporating  3337.877  pounds  of  sea-water,  or  4.483  pounds  of 
water  per  pound  of  coal.  It  was  intended  to  have  made,  on  the  following 
day,  an  experiment,  under  precisely  the  same  circumstances  as  above,  with 
anthracite ; but  it  was  found  impossible  from  the  presence  of  ice  to  work 
the  engine,  the  experiment  was  therefore  only  made  so  far  as  regards  the 
time  of  getting  up  steam,  with  the  following  results,  viz  : 

The  fires  were  lighted  with  the  same  quantity  and  kind  of  wood,  and 
the  same  quantity  of  coal  that  had  been  used  the  day  previous.  At  seven 
hours  and  twenty  minutes  A.  M.  the  temperature  of  the  water  in  the  boiler 
being  38°  F.,  and  that  of  the  boiler  room  32°  F.,  with  the  natural  draft, 
the  temperature  of  the  water  at  eight  hours  and  five  minutes  was  212° 
(steam,)  and  the  boiler  room  43°  F.  Time  to  generate  steam  forty-five 
minutes.  At  eight  hours  and  twenty  minutes  the  steam  pressure  in  the 
boiler  was  thirty  pounds  per  square  inch.  Time  of  obtaining  thirty  pounds 
of  steam  from  water  at  38°  F.  was  one  hour. 

With  the  bituminous  coal  it  will  be  seen  that  it  required  seventy  minutes 
to  obtain  steam  from  water  at  the  temperature  of  32°  F.,  while  it  only 
required  forty-five  minutes  with  the  anthracite ; being  a difference  of  time 
in  this  respect  of  about  thirty-six  per  cent,  of  the  bituminous  time. 

The  data  for  a comparison  of  the  evaporative  values  of  the  coals  was 
obtained  by  another  experiment  as  follows : 

Experiments  with  White  Ash  Anthracite  made  with  the  boilers  of  the 
United  States  Steamer  Fulton,  in  JYew  York  Bay,  January  1,  1852. 

This  experiment  was  made  with  the  steamer  under  way,  while  steaming 
with  steady  pressure  of  steam  and  revolutions  of  the  wheel,  as  follows  ; 

Steam  pressure  {initial)  in  cylinder  per  square  inch  above  the  atmos- 
phere, twenty-five  pounds ; double  strokes  of  piston  per  minute,  twenty- 
one  and  one-third ; cutting  off  at  from  commencement  of  stroke,  three- 
eighths  ; consumption  of  coal  per  hour,  eighteen  hundred  pounds. 

From  the  above  data,  there  was  filled  per  stroke  52.837  cubic  feet  of 
the  space  displacement  of  the  piston,  to  which  add  3.094  cubic  feet  of 
space  comprised  between  cut  off  valve  and  piston,  making  a total  of  55.931 
cubic  feet  of  steam  of  twenty-five  pounds  pressure,  which  would  be  per 
minute  55.931  X42|=2386. 39  cubic  feet,  and  per  hour  143,183.40  cubic 
feet.  Dividing  this  last  number  by  the  relative  bulks  of  steam  of  the 


5 


pressure  generated,  and  the  water  from  which  it  was  generated,  we  obtain 
209.332  cubic  feet  of  sea- water,  which  at  64.3  pounds  per  cubic 
foot,  amounts  to  13,460.047  pounds,  evaporated  by  1800  pounds  of  coal, 
or  7.478  pounds  of  sea- water  per  pound  of  coal. 

3.  Experiment  with  white  ash  anthracite  coal  made  with  the  boilers  of  the 
pumping  engine  at  the  United  States  Dry  Dock,  JSTew  York  JYavy  Yard. 

A comparative  experiment  was  made  with  the  boilers  of  the  pumping 
engine  at  the  New  York  Navy-Yard,  in  October,  1851,  on  the  comparative 
advantages  of  anthracite  and  bituminous  coals  ; all  the  conditions  were  as 
nearly  alike  as  practicable.  With  the  anthracite  coal  a combustion  of  nine 
hundred  and  eighty  pounds  per  hour,  evaporated  a sufficient  quantity  of 
water  to  supply  the  engine  with  steam  of  twelve  pounds  pressure  above 
the  atmosphere,  per  square  inch,  for  four  hundred  and  twenty- five  double 
strokes  of  piston  per  hour,  the  steam  pressures  being  alike  in  both  cases  ; 
the  economical  values  of  the  coals  will  be  represented  by  the  number  of 
double  strokes  of  piston  made,  divided  by  the  quantity  of  fuel  per  given  unit 

of  time  ; or  will  be,  anthracite  ^^=0.4337  : bituminous  0.2673, 

or  the  anthracite  is  better  than  the  bituminous  in  the  proportion  of 

^^'^=1.623  to  1.000. 

0.2673 

It  is  proper  to  remark  that  these  boilers  were  expressly  designed  for 
burning  bituminous  coal. 


COMPARISON. 

The  coals  used  in  these  experiments  were  the  kinds  furnished  by  the 
agents  of  the  government  for  the  use  of  the  United  States  Navy-Yard 
and  Steamers,  and  was  taken  indiscriminately  from  the  piles  in  the  yard 
without  assorting. 

The  bituminous  was  from  the  Cumberland”  mines.  The  anthracite 
was  the  kind  known  as  White  Ash  Schuylkill.” 

From  the  preceding  data,  it  appears  that  in  regard  to  the  rapidity  of 

getting  up”  steam,  the  anthracite  exceeds  the  bituminous  thirty-six  per 
cent. 

That  in  economical  evaporation  per  unit  of  fuel,  the  anthracite  exceeds 
the  bituminous  in  the  proportion  of  7.478  to  4.483  or  66.8  per  cent. 

It  will  also  be  perceived,  that  the  jesult  of  the  third  experiment  on  the 
boilers  of  the  pumping  engine  at  the  New  York  Dry  Dock,  which  experi- 
ment was  entirely  differently  made  and  calculated  from  the  first  and 
second  experiments,  gave  an  economical  superiority  to  the  anthracite  over 
the  bituminous  of  62.3  per  cent.  5 a remarkably  close  approximation  to  the 
result  obtained  by  the  experiments  on  the  “ Fulton^ s^’  boilers,  (66.8  per 
cent.,)  particularly  when  it  is  stated  that  the  boilers  and  grates  of  the 
pumping  engine  were  made  with  a view  to  burning  bituminous  coal,  which 


6 


has  been  used  since  their  completion : while  those  of  the  Fulton”  were 
constructed  for  the  use  of  anthracite.  The  general  characters  of  the  boilers 
were  similar,  both  having  return  drop  flues. 

Thus  it  will  be  seen,  from  the  experiments,  that,  without  allowing  for  the 
difference  of  weight  of  coal  that  can  be  stowed  in  the  same  bulk,  the  en- 
gine using  anthracite  could  steam  about  two-thirds  longer  than  with 
bituminous. 

These  are  important  considerations  in  favor  of  anthracite  coal  for  the 
uses  of  the  Nav}";  without  taking  into  account  the  additional  amount  of 
anthracite  more  than  bituminous  that  can  be  placed  on  board  a vessel  in 
the  same  bunkers,  or  the  advantages  of  being  free  from  smoke,  which  in  a 
war-steamer  may  at  times  be  of  the  utmost  importance  in  concealing  the 
movements  of  the  vessel,  and  also  the  almost,  if  not  altogether,  entire  free- 
dom from  spontaneous  combustion. 

The  results  of  the  experiments  made  last  spring  on  the  United  States 
steamer  Vixen”  were  so  favorable,  that  I recommended  to  the  Bureau  of 
Construction,  &c.,  the  use  of  anthracite  for  all  naval  steamers  at  that  time 
having,  or  to  be  thereafter  fitted  with  iron  boilers  ; particularly  the  steamers 

Fulton,”  Princeton,”  and  Alleghany,”  the  boilers  for  all  of  which 
were  designed  with  a special  view  to  the  use  of  anthracite,  and  with  the 
approval  of  that  bureau. 

The  “ Fulton’s”  bunkers  are  now  filled  with  anthracite,  and  the  con- 
sumptions referred  to  in  the  engineer’s  report  on  that  steamer  show,  during 
the  short  time  she  has  been  at  sea,  that  the  anticipated  economy  has  been 
fully  realized. 

In  view  of  the  results  contained  in  this  report,  I would  respectfully 
recommend  to  the  Bureau  of  Yards  and  Bocks,  the  use  of  anthracite  in  the 
several  Navy-Yards,  and  especially  for  the  engine  of  the  Bry-Bock  at  the 
New  York  Navy- Yard. 

In  conclusion,  I desire  the  approval  of  the  Bureau  to  make  such  investi- 
gations as  my  duties  will  permit,  with  regard  to  the  experience  of  the  dura- 
bility of  copper  boilers,  when  used  with  bituminous  or  anthracite  coal ) 
which  can  be  done  without  any  specific  expenditure. 

The  inquiry  may  prove  highly  important  to  the  Navy  Bepartment,  as 
the  use  of  anthracite  under  copper  boilers  has  been  heretofore  generally 
considered  as  more  injurious  than  bituminous  coal,  and  is  consequently  not 
used  by  government  in  vessels  having  copper  boilers. 

Bespectfully  submitted,  by  your  obedient  servant, 

CHAB.LES  B.  STUART, 

Engineer-in-Chief,  U.  S.  JTavy. 

Commodore  Joseph  Smith, 

Chief  of  Bureau  of  Yards  and  Docks. 


LETTER  OF  THE  ENGINEER-IN-CHIEF  OF  THE  NAVY, 

IN  RELATION  TO  COALS, 

Addressed  to  the  Chairman  of  the  Committee  on  Naval  Affairs. 


May  27,  1852. — Referred  to  the  Committee  on  Naval  Affairs,  and  or- 
dered to  be  printed. 


Office  Engineer-in-Chief,  U.  S.  Navy,  ) 

May  27,  1852.  j 

Sir  : The  Senate,  by  resolution,  having  called  for  my  reports  to  the 
N avy  Department,  giving  the  results  of  several  experiments  to  test  the 
relative  value  of  anthracite  and  bituminous  coals  for  generating  steam,  and 
referred  the  same  to  the  Committee  on  Naval  Affairs,  I have  thought  that 
the  results  obtained  from  additional  tests  and  experiments,  made  in  this 
country  and  England,  would  be  of  service  to  the  committee,  and  trust  that 
the  importance  of  the  subject,  both  to  the  interests  of  the  government  and 
of  individuals,  will  be  considered  a sufficient  apology,  if  any  be  needed,  for 
the  liberty  I have  taken  in  addressing  you  this  communication. 

It  should  be  remembered  that  what  is  required  to  be  known  on  this  sub- 
ject, is  neither  the  absolute  nor  relative  evaporation  by  coals  under  condi- 
tions that  never  occur  in  practice^  (as  too  many  experiments  are  conducted,) 
but  the  facts  to  be  determined  are,  the  results  which  can  be  obtained  from 
them  under  the  ordinary  circumstances  in  which  they  are  used  in  marine 
boilers. 

With  this  view  I have  prepared  the  following  tabular  statement,  showing 
the  actual  evaporation  of  water  effected  by  bituminous  and  anthracite  coals 
in  the  boilers  of  several  naval  steamers,  and  in  those  of  some  transatlantic 
and  river  steamers  plying  to  and  from  New  York  the  past  few  years. 

This  table,  therefore,  from  being  prepared  with  care  from  the  steam  logs 
of  the  different  vessels  (those  of  the  navy  being  on  file  in  this  office)  is  of 
great  value ; more  so,  undoubtedly,  than  if  the  results  had  been  obtained 
from  a series  of  special  experiments  made  under  circumstances  not  normal 
to  the  practice,  which  results,  therefore,  must  be  extensively  modified  be- 
fore they  could  be  received  for  practical  guides. 

The  table  includes  all  the  cases  I have  been  able  to  obtain  at  this  time, 
where  the  data  were  unexceptionable ; it  extends  in  most  instances  over  a 
course  of  several  years  steaming,  and  the  average  evaporation  thus  obtained, 
although  not  equal  sometimes  to  the  maximum  of  special  experiments,  is, 
in  my  judgment,  more  entitled  to  confidence  than  any  single  experiment 
made  with  greater  critical  accuracy,  but  on  too  small  a scale  for  trust- 
worthy results. 


8 


Of  the  latter  character,  I should  rank  those  of  W.  R.  Johnson,  Esq., 
made  under  the  directions  of  the  Navy  Department,  in  1843,  in  the  report 
of  which  he  states  that  on  each  sample  of  coal  were  made  from  one  to  six 
trials,  according  to  the  quantity  furnished.  The  coal  consumed  in  one  trial 
never  exceeded  1567  pounds — this  being  the  greatest  quantity  which  the 
apparatus  could  receive  in  the  period  allotted  to  each  experiment,  including 
the  time  required  for  cleaning  out  the  residue,  making  the  necessary  ad- 
justments and  preparing  for  a new  trial.  The  total  weight  of  coal  consumed 
in  the  trials  of  evaporative  power  has  been  nearly  sixty-two  and  a half 
tons  ; and  the  weight  used,  on  an  average,  nine  hundred  pounds  per  trial” 
— being  less,  it  will  be  seen,  than  half  a ton  per  trial,  or  not  three  tons  for 
the  greatest  number  of  trials  made  with  any  one  kind  of  coal,  not  equal  to 
a two  hours’  consumption  of  an  ordinary  sea  steamer. 

These  experiments  were  not  only  very  limited  in  their  extent,  but  were 
made  with  a boiler  entirely  different  in  its  construction  from  those  in  naval 
and  sea  steamers,  and  not  at  all  adapted  for  that  service,  and  cannot  therefore 
be  compared  in  value  to  the  following  practical  tests,  deduced  from  the 
consumptions  of  hundreds  of  tons  of  coals  on  each  steamer  named  and  in 
actual  service. 


TABLE  OF  PRACTICAL  TESTS  OF  DIFFERENT  VARIETIES  OF  COAL. 


NAME  OP  VESSEL, 


TRADE. 


£ c bco 

S 

a 3 o V' 

o)  O - oi  — 


£ O bco 

w 0)  . 

£ (D  S 
0,5  = ’^  • 
<0  ^ CTo 

o S S'l.s 

^ - S = S 

fe  5 2 

lilr 


; oii  c5 


REMARKS. 


Michigan 

Mississippi 

Spitfire 

Engineer 

Alleghany  .... 

Iris 

Princeton 

Princeton 

Princeton 

Princeton 

McLane 

Bibb 

United  States.. 

Herman 

Baltic 

City  of  Pittsburg 
New  W orld  . . 
Commodore. . 
Roanoke 


United  States  Navy 


do 

do 

do 

do 

do 

do 

do 

do 

do 


do 

do  . . 

do 

do  . . 
do  . . 

do  . 
do  . 
do  . 
do  . 


United  StatesTreas’y 

, . do do 

Transatlantic  packet 

, . do do  . 

, . do do  . 

do do  . 

Hudson  River 

Long  Island  Sound  . 
N . Y ork  and  N orfolk 


Averages 


POUNDS'. 

*5  000 
t4.780 
t4  870 
t4.531 

fs.eoo 

t5.180 

t6.666 

§5.372 


POUNDS 


7 554 
6 639 

7.030 

6.030 
7.480 


t4  487 


8.555 


t4.930 


8 022 
7.262 
6.554 


Fresh  water. 

Sea  water, 
do 
do 
do 

Sea  water  & old  flue  boil. 
Sea  water  and  new  boil, 
do  do 

do  do 

Sea  water  and  old  boilers 
Sea  water, 
do 
do 

Sea  water  and  old  boilers 
Sea  water, 
do 
do 
do 
do 


10)51.416 
5.142 


9)65.116' 

7.235* 


Pittsburg  coal.  f Cumberland  coal.  | Virginia  coal.  § Scotch  coal. 


9 


From  the  averages  of  the  above  table  it  will  be  seen  that  the  economical 
evaporation  by  the  anthracite  exceeded  that  by  the  bituminous  in  the  pro- 
portion of  7.235  to  5.142,  or  about  forty-one  per  centum  of  the  latter. 

In  the  experiments  made  on  coals  by  Playfair  and  De  la  Beche,  by  order 
of  the  British  government,  in  1848,  I find  eleven  varieties  of  Welsh  coals 
having  a constitution  almost  identical  with  the  nine  specimens  of  various 
Pennsylvania  anthracite,  experimented  on  by  J ohnson,  viz  : 


Welsh  anthra- 
cite. 

Pennsylvania 

anthracite. 

Fixed  carbon  

87.54 

88.54 

Sulphur 

0.79 

0.05 

Other  volatile  matter 

5 50 

5 17 

T’,  art  by  ma.t.f'fir  , 

6.48 

6.51 

100.31 

100.27 

The  average  evaporation  of  water  by  the  Welsh  anthracite  and  by  the 
Pennsylvania  anthracite  was  as  follows  : 

Fresh  water  evaporated  from  the  temperature  of  212  deg.  F.,  by  one  pound  of  coal 

By  Welsh  anthracite pounds, . . . 9.263 

By  Pennsylvania  anthracite do 9.590 


Thus  far  there  is  a very  close  agreement  between  the  results  obtained  by 
the  different  experimenters  from  substantially  the  same  coal — that  coal 
being  anthracite. 

In  the  experiments  of  Playfair  and  Be  la  Beche,  above  cited,  I find  three 
varieties  of  Welsh  bituminous,  three  varieties  of  Scotch  bituminous,  and 
one  variety  of  English  bituminous,  having  a constitution  almost  identical 
with  the  five  specimens  of  Maryland  (Cumberland)  bituminous  coal  experi- 
mented on  by  Johnson. 


Welsh,  Scotch, 
and  English 
bituminous. 

Maryland(Cum- 
berland)  bitu- 
minous. 

r.aTbon 

75.00 

1.47 

14.55 

8.97 

75.05 

Sulphur 

mhpr  volatile  ma,tter  

15  45 

9.49 

Earthy  matters,  &c 

99.99 

99.99 

The  average  evaporation  by  the  Welsh,  Scotch  and  English  bituminous 
and  by  the  Cumberland  bituminous  was  as  follows,  viz : 


Fresh  water  evaporated  from  a temperature  of  212  deg.  F.,  by  one  pound  of  coal 

By  Welsh,  Scotch  and  English  bituminous pounds. . . . 8.02 

By  Maryland  (Cumberland)  bituminous do 9.93 


Here  is  a great  discrepancy  between  the  results  obtained  by  the  two 
experimenters  on  substantially  the  same  coals ; Johnson  making  the  Cum- 
berland bituminous  better  than  the  British  bituminous  in  the  proportion  of 
no  less  than  twenty-four  and  a half  per  centum  of  the  latter.  Had  a 
similar  dilference  been  found  in  the  case  of  anthracite  between  the  results 
of  the  two  experiments,  it  might  have  been  accounted  for  by  a difference 
of  boiler  or  method  of  conducting  the  experiments. 

From  an  investigation  of  the  two  kinds  of  boilers  employed,  I am  of 
opinion  that  though  in  their  proportions  separately  different,  yet  in  the 
aggregate  they  were  equivalent ; an  opinion  justified  also  by  the  equality 
of  results  obtained  with  anthracite. 

The  results,  then,  of  Johnson’s  experiments  are  that  Cumberland  bitumi- 
nous exceeds  the  Pennsylvania  anthracite  in  economical  evaporation,  four 
per  centum  of  the  latter ; while  the  results  from  the  English  experiments, 
on  substantially  the  same  coals,  make  the  economical  evaporation  of  the 
anthracite  to  exceed  that  of  the  bituminons  over  twenty-four  per  centum  of 
the  latter. 

I would  here  beg  leave  to  remark  that  there  were  several  important  facts 
attending  the  experiments  of  Professor  Johnson,  which,  rightly  understood, 
would  greatly  modify  his  results  ; and  which  facts  it  is  absolutely  neces- 
sary to  consider  in  order  to  arrive  at  correct  practical  information.  One 
of  the  most  important  of  these  is  the  rapidity  of  combustion,  which  is  ordi- 
narily measured  by  the  number  of  pounds  of  coal  consumed  per  hour  per 
square  foot  of  grate  surface,  the  average  quantity  of  which  in  marine  boilers 
may  safely  be  taken  at  fifteen  pounds. 

In  Johnson’s  experiments,  however,  the  consumption  of  Cumberland  bitu- 
minous coal  was  at  the  rate  of  only  pounds,  and  of  anthracite 
pounds ; an  average  of  less  than  half  the  practical  rate  of  consumption. 

It  is  obvious,  therefore,  that  the  rapidity  of  combustion  being  an  impor- 
tant element  in  determining  the  evaporative  efficiency  of  different  coals, 
that  in  any  experiments  made  to  ascertain  this  efficiency  for  marine  boilers, 
the  rapidity  of  combustion  should  be  about  the  average  of  what  occurs  in 
actual  practice  at  sea. 

Again  : the  importance  of  the  rate  of  combustion  in  effecting  the  results 
to  be  obtained  from  anthracite  or  bituminous  coals,  are  well  signalized  in 
the  following  extract  from  a paper  by  chief-engineer  Isherwood,  U.  S. 
Navy,  published  in  “Appleton’s  Mechanic’s  Magazine,”  etc.,  for  October, 
1851,  page  621,  viz  : — 

“ In  the  combustion  of  bituminous  coal,  time  is  the  important  element, 
and  a slow  rate  of  combustion  with  low  velocity  of  draught  is  necessary  for 
obtaining  high  evaporative  results,  and  for  the  following  reasons,  viz  : The 
bituminous  portion  of  the  coal  is  volatilized  and  separated  from  the  fixed 
carbon  part  at  a lower  temperature  than  is  required  for  its  ignition,  that  is, 
than  is  required  for  its  chemical  union  with  oxygen.  In  this  gaseous  state, 
occupying  the  furnaces  and  flues  of  the  boiler,  it  can  only  be  ignited  by 
being  mixed  with  atmospheric  air  at  a sufficiently  high  temperature  5 the 
element  of  time  is,  therefore,  doubly  important ; first,  to  allow  the  gases  to 
become  intimately  mixed  with  the  atmospheric  air ; second,  to  allow  them 
to  acquire  the  necessary  high  temperature.  If  now,  by  means  of  a power- 


11 


ful  draught,  the  gases,  having  only  the  low  temperature  due  to  their  vola- 
tilization, be  driven  so  quickly  through  the  flues  and  out  of  the  chimney  of 
the  boiler  as  not  to  allow  them  time  enough  to  acquire  the  proper  tempera- 
ture for  combustion,  and  to  have  the  proper  mixing  with  the  atmospheric 
air,  a great  loss  of  effect  must  inevitably  follow. 

For  the  economical  combustion,  then,  of  bituminous  coal  in  generating 
steam,  there  should  be  a slow  rate  of  burning,  or  a small  amount  consumed 
per  unit  of  time  per  unit  of  surface.” 

In  the  combustion  of  anthracite  coal,  however,  the  above  general 
observations  do  not  apply.  Considering  the  principal  portions  of  the  an- 
thracite to  be  fixed  carbon,  there  will  of  course  be  no  volatilization  of 
bitumen  at  a lower  temperature  than  what  is  required  for  the  ignition  of 
the  fixed  carbon ; the  coal  will  consequently  remain  unchanged  until  the 
temperature  is  sufiiciently  high  for  its  combustion,  that  is,  for  the  com- 
bustion of  its  fixed  carbon ; a forced  draught  cannot,  therefore,  carry  off 
the  fuel  before  it  is  ignited,  and  in  this  view  velocity  of  draught  is  com- 
paratively unimportant.  Again,  combustion  with  the  anthracite  is  effected 
solely  by  the  contact  of  the  air  with  their  solid  surfaces  ; there  is  there- 
fore no  mixing  to  be  done,  and  consequently  no  time  required  to  do  it  in. 
Here,  then,  under  two  important  conditions,  great  velocity  of  draught, 
which  is  highly  detrimental  to  the  economical  combustion  of  bituminous,  is 
unimportant  in  the  combustion  of  anthracite  coal.” 

Taking  the  above  views  to  be  correct,  which  it  is  believed  they  are,  it 
will  be  perceived  that  the  very  slow  rate  of  combustion  used  with  the 
bituminous  coal  in  Johnson’s  experiments,  (a  rate  utterly  out  of  question 
with  marine  boilers)  was  in  the  highest  degree  favor  able  for  the  development 
of  the  full  heating  power  of  the  bituminous  coal ; now  as  this  rate  of 
combustion  is  impracticable  in  marine  engines,  a very  great  correction  for 
inferior  results  to  be  obtained  by  the  faster  rate  of  combustion  must  be 
made,  in  order  to  obtain  their  practical  value.  With  the  anthracite,  the 
very  slow  rate  of  combustion  used  was  positively  a disadvantage,  as  it 
could  not  keep  the  whole  mass  sufiiciently  high  to  enable  the  fixed  carbon 
to  take  up  the  oxygen  of  the  air  as  fast  as  the  latter  entered;  consequently 
it  exerted,  in  a considerable  degree,  a cooling  power. 

Further,  it  is  generally  acknowledged  that  the  quantity  of  carbon  in 
coals  is  at  least  an  index,  if  not  a full  measure  of  their  practical  heating 
power.  This  idea  is  entertained  by  Johnson  himself,  and  is  announced  in 
his  work  on  coals,  published  in  1850,  pages  118,  123  and  124,  viz  : 

The  British  experimenters  continued  their  analysis  of  the  coals  till 
every  sample  had  been  submitted  to  both  proximate  and  ultimate  determi- 
nation. In  the  American  experiments  time  was  not  allowed  before  the  re- 
port was  demanded,  for  extending  the  ultimate  analyses  to  more  than  one- 
eighth  part  of  the  samples.  From  such  trials  as  were  made,  the  deductions 
which  appeared  to  be  authorized  by  a careful  comparison  between  the  con- 
stituents of  the  coals  and  their  evaporative  efficiency  was,  that  the  latter  de- 
pended upon  the  total  amount  of  carbon  in  the  coal.  If  hydrogen  had  been, 
as  many  European  chemists  had  contended,  the  more  efficient  element, 
weight  for  weight,  then  all  highly  bituminous  coals  ought  to  have  presented 
a greater  heating  power  than  those  of  lower  bituminousness.” 


12 


Botli  the  American  and  British  experiments  concur  in  proving  the  re- 
verse of  this  to  he  the  fact.’’ 

This  development  finally  sets  aside  the  old  calculations  about  the 
relative  heating  powe?'s  of  carbon  and  of  the  hydrogen  in  coals.  By  the 
principle  of  that  calculation,  any  coal  having  a high  degree  of  bituminous- 
ness  ought,  in  consequence  of  the  large  proportion  of  hydrogen  in  its 
bitumen,  to  possess  a much  higher  heating  power  than  any  coal  of  lower 
bituminousness.  The  reverse  of  this  fs  true.  The  higher  the  bituminous- 
ness, or,  in  other  words,  the  greater  the  proportion  of  volatile  matter  a 
coal  contains,  the  less  is  its  available  heating  power.  The  fact  has  been 
pointed  out  in  former  publications  of  the  writer,  that  when  solid  hydrogen 
(that  being  its  state  in  coals)  is  converted  by  the  effect  of  heat  into 
gaseous  hydrogen,  it  requires  for  this  change  a large  amount  of  heat,  as 
experimentally  proved  in  the  manufacture  of  illuminating  gas.  The  hy- 
drogen thus  brought  to  the  gaseous  state,  assumes  the  same  bulk  at  a 
given  temperature,  say  212^,  as  it  will  retain  at  the  same  temperature 
when  converted  into  vapor  of  water  under  the  atmospheric  pressure  ; and 
consequently,  unless  we  can  suppose  the  capacity  for  heat  of  gaseous  hy- 
drogen, bulk  for  bulk,  to  be  greater  than  that  of  the  vapor  of  water,  we 
can  conceive  no  reason  why  it  should  give  out  more  heat  in  combining  with 
oxygen  than  it  had  taken  up  in  being  converted  into  gas.  The  British 
Commissioners  refer  to  this  view  of  the  subject,  but  do  not  clearly  express 
an  opinion  of  its  validity. 

Fortunately  their  silence  is  of  less  importance,  as  their  own  experi- 
ments furnish  abundant  proofs  of  the  correctness  of  the  principle.  In  order 
more  clearly  to  exhibit  the  independence  of  hydrogen  efficiency  in  computing 
heating  powers  of  analyses,  we  have  placed  in  the  above  table  the  per  cent- 
age  of  hydrogen  found  in  each  sample  of  coals.  From  this  column  the 
averages  are  deduced,  and  a glance  will  show,  that  so  far  as  any  law  or 
relation  is  perceptible,  the  coals  of  highest  heating  powers  are  those  which 
have  the  lowest  per  centage  of  hydrogen.”  The  table  above  referred  to 
condensed  from  Johnson,  stands  as  follows,  viz  : 


Hydrogen. 

Carbon. 

Steam  by  ex- 
periment. 

Steam  by  cal- 
culation. 

Per  cent. 

Per  cent. 

Pounds. 

Potinds. 

Four  coals, 

average 

4.13 

74.15 

7.78 

8.03 

Do 

• do 

4.30 

76.63 

8.35 

8.37 

Do 

.do 

4.57 

79.67 

8.65 

8.60 

Do 

.do 

4.88 

81.06 

8.89 

8.75 

Do 

.do 

4.17 

85.68 

9.17 

9.25 

Do 

.do 

4.55 

88.12 

9.50 

9.51 

Do 

.do 

4.47 

88.99 

9.75 

9.75 

“Thus  the  four  coals  having  a heating  power  of  7.78,  have  excess  of 
hydrogen  4.13  ; the  four  having  heating  powers  of  9.17,  have  of  oxygen  in 
excess  4.17.  It  will  also  be  noted  that  an  intermediate  class  of  coals 
having  a heating  power  of  8.65,  has  a higher  per  centage  of  hydrogen  than 
either  of  the  above,  viz : 4.57.  This  is  as  we  might  expect  to  find  it,  if 


13 


the  hydrogen  he  truly  without  efficiency  in  the  practical  use  of  coal.  In- 
deed, the  hydrogen  appears  from  the  practical  tests  thus  far  adduced,  no 
more  to  merit  the  consideration  as  an  element  of  evaporative  effciency  in 
coal,  than  an  equal  weight  of  silicia,  alumina,  oxide  of  iron,  or  other  inert 
substance  found  in  its  earthly  residuum  or  ashd’’ 

It  appears  to  be  difficult  to  reconcile  the  foregoing  and  well-established 
fac^s,  with  the  numbers  given  by  Professor  Johnson  as  the  results  of  his 
experiments  on  anthracite  and  Cumberland  (bituminous)  coals,  the  former 
containing  per  centum  of  carbon  and  the  latter  only  75  , per 

centum,  while  he  makes  the  XxHqy  four  per  centum  better  than  the  former, 
while  it  should  have  been  as  above  demonstrated  the  reverse  in  the  pro- 
portion of  to  75, or  eighteen  per  centum. 

The  results  of  the  British  improvements  on  substantially  the  same  coals, 
viz  : containing  relatively  87,^,,^  and  75  per  centum  of  carbon,  gave  for 
the  former  a greater  efficiency  of  twenty-four  and  a half  per  centum, 
making  a difference  in  the  results  of  over  twenty-eight  per  centum. 

A large  number  of  experiments  and  practical  tests  might  be  cited  to  fur- 
ther prove  the  greater  efficiency  of  anthracite  over  bituminous  coals,  in 
proportion  very  nearly  as  the  element  of  carbon  was  found  ; but  they  would 
swell  this  paper,  now  already  too  extended.  I have  therefore  confined  the 
comparison  to  a few  experiments  of  admitted  correctness,  to  illustrate  the 
facts,  and  in  conclusion  would  add,  that  I agree  fully  with  the  views 
expressed  in  Professor  Johnson’s  report,  “ that  for  the  purpose  of  steam 
navigation,  therefore,  the  rank  most  important  to  be  considered  (in  different 
coals)  is  in  the  order  of  their  evaporative  power  under  given  bulks.  This 
is  obviously  true,  since,  if  other  things  be  equal,  the  length  of  a voyage 
must  depend  on  the  amount  of  evaporative  power  effected  by  the  fuel  which 
can  be  stowed  in  the  bunkers  of  a steamer,  always  of  limited  capacity. 
With  this  scale  of  value,  however,  must  be  combined  the  relative  freedom 
from  clinker,  and  the  maximum  rapidity  of  action ; while  the  rapidity  of 
ignition  is  of  inferior  importance,  but  may  deserve  some  consideration 
where  short  V03^ages,  frequent  stoppages,  and  prompt  commencement  of 
action  are  demanded” — all  of  which  qualities  I think  have  been  from  prac- 
tical results  found  to  be  more  fully  combined  in  the  white  ash  anthracite 
of  Pennsylvania  than  any  other  known  coal.  I therefore  fully  concur  in  the 
opinion  of  Professor  Johnson,  expressed  in  his  work  on  coals,  published  in 
1850,  page  160. 

“ In  conclusion  I may  observe,  that  while  these  analyses  demonstrate 
the  high  density  and  compactness  of  this  coal  (anthracite)  fitting  it  for  the 
purposes  of  steam  navigation,  for  which  these  qualities,  combined  with  great 
heating  power,  are  of  primary  importance,  they  also  show,  that  for  the  va- 
rious arts  and  for  domestic  consumption,  its  properties  are  calculated  to 
sustain  the  high  character  of  the  central  coal-field  of  Pennsylvania,  for  the 
concentrated  and  durable  heat  which  it  furnishes,  and  the  absence  of  those 
ingredients  which  might  interfere  with  its  useful  application.” 

I have  the  honor  to  be,  sir,  with  great  respect,  your  obedient  servant, 

CHARLES  B.  STEWART, 
Engineer-in- Chief,  U.  S.  JV. 


i 


